fix(FloatingPanel): Reuse closest function (#12007)

packages/vant/src/floating-panel/FloatingPanel.tsx

@@ -9,6 +9,7 @@ import {
 // Utils
 import {
   addUnit,
+  closest,
   createNamespace,
   makeArrayProp,
   makeNumericProp,
@@ -88,11 +89,6 @@ export default defineComponent({
       return moveY;
     };
 
-    const closest = (arr: number[], target: number) =>
-      arr.reduce((pre, cur) =>
-        Math.abs(pre - target) < Math.abs(cur - target) ? pre : cur
-      );
-
     let startY: number;
     const touch = useTouch();